In a liquid crystal display panel, etc., in order to suppress electromagnetic interference (EMI) during data transmission, current-mode data transmission, in which a current corresponding to a data signal is transmitted and received, may be adopted.
An example of the current-mode data transmission described in Patent Document 1 is described below. A transmission line is driven by a transistor in a transmitter circuit connected to one end thereof. In a receiver circuit, a current-to-voltage conversion device (a diode-connected transistor) and a transistor which serves as a current source are connected in series, and the other end of the transmission line is connected to a node therebetween.
A drive current Id which flows into the transmitter circuit causes a bias current Ib of the current-to-voltage conversion device in the receiver circuit to change. The bias current Ib undergoes current-to-voltage conversion by the current-to-voltage conversion device, and is input to a comparator as an internal voltage signal. The other transmission line is similarly configured, and a transmission data signal is derived from a difference of the two voltages which are input to the comparator.
Since, in this transmission scheme, a voltage change (Id*gm) determined by the drive current Id and a transconductance gm of the current-to-voltage conversion device appears as a voltage amplitude between the transmission lines, the voltage amplitude becomes much smaller than that of digital transmission (the amplitude is approximately 3.3 V) by a general CMOS (complementary metal oxide semiconductor) circuit, thereby enabling to contribute to a reduction of EMI.
PATENT DOCUMENT 1: Japanese Patent Publication No. 2005-236930